Alcohols and Carboxylic Acids

alcohol

An organic compound containing a hydroxyl group, -OH

What are the examples of alcohols?

• methanol

• ethanol

• propanol

• butanol

functional group

An atom, or group of atoms, that determines the main chemical properties of an organic compound.

What’s alcohol functional group?

OH

Methanol

CH3OH

Ethanol

C2H5OH

Propanol

C3H7OH

Butanol

C4H9OH

By what process is ethanol produced?

fermentation

Equation for fermentation

glucose → ethanol + carbon dioxide

Uses alcohols

• fuels - burn well

• solvents - water soluble

• alcoholic drinks - ethanol

Solubility in water (alcohols)

• alcohols with the shortest hydrocarbon chains, eg methanol, ethanol or propanol mix easily to produce a solution

• Solubility decreases as the length of the alcohol molecule gets longer

• Butanol is less soluble than propanol may not mix easily

• forms neutral solution

Reaction with sodium (alcohol)

forms hydrogen

Oxidation of alcohols

The alcohols can also be oxidised without combustion to produce carboxylic acids

forms carbon dioxide and water

Carboxylic acid

A homologous series of compounds that contain the carboxyl functional group, -COOH.

Methanoic acid

HCOOH

Ethanoic acid

CH3COOH

Propanoic acid

C2H5COOH

Butanoic acid

C3H7COOH

Properties of carboxylic acids

• dissolve in water to form acidicsolutions with pH values less than 7

• react with metals to form a salt and hydrogen

• react with bases to form a salt and water

• react with carbonates to form a salt, water and carbon dioxide

Carboxylic reaction with alcohols

• react with alcohols to make esters

• Esters contain the functional group -COO-.

• alcohol + carboxylic acid → ester + water

Strength of carboxylic acids

• Weak acids

• don’t contain many hydrogen ions compared with a solution of a strong acid with the same concentration

• pH of a weak acid will be higher than the pH of a strong acid